''Schloenbachia'' is a genus of

ammonoid Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttlefish) ...

cephalopods from the

Cenomanian The Cenomanian is, in the ICS' geological timescale, the oldest or earliest age of the Late Cretaceous Epoch or the lowest stage of the Upper Cretaceous Series. An age is a unit of geochronology; it is a unit of time; the stage is a unit in the s ...

stage of the Upper Cretaceous, and type for the Schloenbachiidae, a family within the ammonitid

Hoplitoidea Hoplitoidea, formerly Hoplitaceae, is a superfamily of mostly Upper Cretaceous ammonites comprising families united by a similar suture pattern with multiple similar elements that tend to decrease in size going toward the umbi ...

.Arkell ''et al.'', Mesozoic Ammonoidea; Treatise on Invertebrate Paleontology, Part L, 1957. ''Schloenbachia'' was named by Newmayer, 1875, the type species is Schloenbachia varians (Sowerby 1817). The genus has been found in Europe (France, Germany, England), the Middle East (Iran), and North America (California, Oregon).

Species

''Schloenbachia varians''

''Schloenbachia varians'', known from Europe and Iran, is a highly varied species with a number of possible synonyms. Variations include ''S. varians'' (var) ''subvarinas'', ''S.v''. (var) ''subtuberculata'', ''S.v''. (var) ''ventricosa'', and ''S.v''. (var) ''varians''. ''Schloenbachia varians'' comprises a highly variable group of medium-sized, involute and compressed to evolute and highly inflated, weak to strongly keeled ammonites, most all of which bear umbilical and lower lateral tubercles. Compressed forms may be smooth and constricted. More inflated forms usually have flexuous ribs that arise from lower lateral tubercles ending in strong clavi at the ventrolateral ends. The variations included cannot be regarded as geographic subspecies or successive chrono-subspecies, but reflect a high degree of variability in shell form and ornament (phenotypic plasticity) in ''S. varians''.

''Schloenbachia'' in western North America

A suite of species attributed to ''Schloenbachia'' have been described from Upper Cretaceous sediments in California and Oregon (Chico Formation and equivalents), including among others ''Schloenbachia chicoensis'', ''S. knighteni'', ''S. multicostata'', ''S. oregonensis'', and ''S. siskiyouensis''. These differ in the nature of the ribbing, tuberculation, and keel as well as the degree of compression or inflation of the shell. Most come from northern California and Oregon, however two species ''Schloenbachia knighteni'' and ''Schloenbachia siskiyouensis'' have been found in the coastal mountains in southern California east of Santa Anna.Silverado Canyon Natural area
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References

Hoplitoidea Ammonitida genera Cretaceous ammonites Ammonites of Europe {{Ammonitina-stub